Vegetables lose their freshness due to temperature, humidity, environmental gasses, microbes, and light. The vegetable is alive, so that it breathes and transpires on its surface. To maintain the freshness, it is necessary to control the breath and the transpiration. Numbers of vegetables, except the ones that fall in disorder due to a low temperature, can be controlled the breath by a low temperature and can be prevented from the transpiration by a high humidity. In recent years, a home-use refrigerator has employed a closed vegetable crisper for keeping the vegetable fresh. The vegetable stored in this crisper can be cooled at an appropriate temperature, and yet a high humidity is kept in the crisper in order to prevent the vegetable from transpiring. Some of these high-humidity keeping devices use a mist atomizer.
A conventional refrigerator having this kind of mist atomizer produces mist with an ultrasonic mist device for humidifying the inside of a vegetable compartment when the inside of the compartment stays at a low humidity, thereby preventing the vegetable from transpiring. This is disclosed in, e.g. Patent Document 1.
FIG. 51 shows a refrigerator having a conventional ultrasonic mist device disclosed in Patent Document 1. FIG. 52 shows a perspective view enlarging an essential part of the ultrasonic mist device. As shown in FIG. 51, vegetable compartment 21 is placed at a lower part of main housing 26 of refrigerator 20, and its open front can be closed by door 22 of a drawer, which a user can slide-out. Partition board 2 separates vegetable compartment 21 from a refrigerator compartment (not shown) placed over compartment 21.
Door 22 of the drawer equipped with hanger 23 fixed to the inside of door 22, and vegetable crisper 1 which accommodates foods, e.g. vegetables, is mounted to this hanger 23. The upper opening of vegetable crisper 1 can be sealed with lid 3. Defrosting chamber 4 is placed inside vegetable crisper 1, and chamber 4 is equipped with ultrasonic mist device 5.
As shown in FIG. 52, ultrasonic mist device 5 includes mist atomizing port 6, water storage tank 7, humidity sensor 8, and hose receptacle 9. Tank 7 is connected to defrosted water hose 10 via receptacle 9, and hose 10 includes purifying filter 11 which purifies the defrosting water.
The operation of the foregoing refrigerator is described hereinafter. A heat exchanging evaporator (not shown) cools the air, which then flows along the outer face of vegetable crisper 1 and lid 3, thereby cooling crisper 1 and the foods accommodated inside thereof. The defrosted water produced by a evaporator during the operation flows through defrosted water hose 10, where the water is purified by purifying filter 11, and is supplied to water storage tank 7 of ultrasonic mist device 5.
Then when humidity sensor 8 senses that the humidity in the storage compartment is not higher than 90%, mist maker 5 starts humidifying, so that the humidity can be adjusted at an appropriate level for the vegetables stored in vegetable crisper 1 to be kept fresh.
When humidity sensor 8 senses that the humidity in the storage compartment is higher than 90%, mist maker 5 stops excessive humidifying. Mist maker 5 thus can quickly humidify the inside of vegetable crisper 1 and keep the inside always at a high humidity, which then allows controlling the transpiration of the vegetables, thereby keeping the vegetables fresh.
Another refrigerator equipped with an ozone-water mist maker is also known in the market; this refrigerator is disclosed in, e.g. Patent Document 2, and includes an ozone generator, an exhaust port, a water supply path directly connected to a water pipe, and an ozone water supply path, which connects to the vegetable compartment. The ozone generator connects to a water supplier directly connected to the water pipe, and the exhaust port connects to the ozone water supply path. An ultrasonic element is placed in the vegetable crisper. The ozone generated in the ozone generator contacts with water, and is turned into ozone-water which works as processing water. The ozone water is supplied to the vegetable compartment, where the water is turned into mist by the ultrasonic oscillator, and the mist is atomized in the compartment.
Although it is not shown in the drawings, a refrigerator is known as employing a negative-ion generator, a centrifugal force and Coriolis force generator, and a gas-liquid separator combined together for maintaining the freshness of vegetables. This refrigerator is disclosed in, e.g. Patent Document 3.
The centrifugal force and Coriolis force generator carries out an ion-dissociation process, a drop-activation process, and a gas-molecule ionization process, thereby generating adduct negative ions of water molecules in the air. The gas-liquid separator separates the air containing the negative ions from the drops, thereby supplying the air to storage room 8, which is then kept at a temperature lower than an ordinary temperature and at a humidity over 80%, and the air therein contains over 1,000 negative ions/cc for storing foods.
Storage room 8 filled with this highly humid air allows cleaning up the inside of room 8 and maintaining the inside of room 8 germfree, so that the foods can be kept fresh thanks to a germ-removing function and a deodorizing function of the negative ions contained in the air. These functions have an anabatic advantage for animals and plants.
However, the foregoing conventional structure vibrates the water or ozone water with the ultrasonic oscillator, thereby making mist. The misted water particles or misted ozone water particles cannot become fine particles, so that the mist cannot be atomized uniformly in storage room 8. The mist thus attaches to the surface of the food at a low ratio. If an atomizing amount is increased or the atomizing is lasted for a long time in order to increase the attachment ratio, the vegetable is spoiled by the water, or dew is formed in storage room 8.
The conventional structure discussed above supplies water to the mist maker by using the defrosted water stored in the tank or the running water, so that the structure needs the hose for the defrosted water, the purifying filter, or the water supply path directly connected to the water pipe. This structure is thus obliged to be complicated.
The mechanism that ionizes the drops in the storage room becomes bulky, so that it does not fit for the home-use refrigerator. A simple ionization will give the drops so poor oxidizing force that a little advantage can be expected.
An atomizing of the mist in the refrigerator compartment, which is roughly sealed and is kept at a low temperature, needs some care in order to carry out a uniform and stable mist atomizing for avoiding such problems as excessive dew formation due to excessive atomizing amount or an inconvenience due to the mist atomizing in a drought status. However, the conventional structures discussed above cannot adjust the amount of mist produced although the mist is atomized in order to keep the storage room at a high humidity. It is thus possible that an excessive mist atomizing will form puddles in the room, or spoil the vegetables stored in the room with the water.    Patent Document 1: Unexamined Japanese Patent Publication No. H06-257933    Patent Document 2: Unexamined Japanese Patent Publication No. 2000-220949    Patent Document 3: Unexamined Japanese Patent Publication No. H07-135945